Investigation of effective parameters on thermal efficiency in a porous channel under local thermal equilibrium conditions
Subject Areas : Renewable Energyzohreh poursharif 1 , Hesamoddin SALARIAN 2 , Kourosh Javaherdeh 3 , majid Eshagh Nimvari 4
1 - Department of Mechanical Engineering, Nour Branch, Islamic Azad University, Nour, Iran.
2 - Department of Mechanical Engineering, Nour Branch, Islamic Azad University, Nour, Iran. *(Corresponding Authors)
3 - Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran.
4 - Faculty of Engineering, Amol University of Special Modern Technologies, Amol, Iran
Keywords: porous channel, Darcy number, non-Newtonian fluid, local thermal equilibrium.,
Abstract :
Background & Objective: By improving the performance of the heat exchanger, it is possible to reduce the size and production costs of the heat transfer, and this leads to a reduction in fuel consumption and better environmental protection. To this purpose, engineers have proposed several ways to increase the heat transfer. The heat transfer rate of a turbulent non-Newtonian fluid flow in a heat exchanger with partially porous media is numerically investigated in this paper. The effects of power-law index of the fluid and Darcy number on the heat transfer rate and thermal performance of turbulent flow are studied and compared to each other.
Material and Methodology: The research model is simulated in the FLUENT computational fluid dynamics software using Finite Volume Method and the flow and energy equations are discretized up to the second order upwind.
Findings: The pseudo-plastic fluid has the highest heat transfer rate and thermal performance compared to Newtonian and dilatant fluids. According to the findings, the heat transfer rate and thermal performance increase with decreasing Darcy number. Investigation of the effect of non-dimensional porous layer area (S) on the Nusselt number and thermal efficiency in different Darcy numbers shows that, the Nusselt number has the highest value in S=0.9 and thermal efficiency has the highest value in S=0.76.
Discussion and conclusion: S=0.76 is the optimal porous layer thickness. Therefore, porous layer with S=0.76, and the pseudo-plastic fluid are recommended for the optimal thermal efficiency.
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